Control apparatus



Aug. 17, 1937.

D. E. NOBLE CONTROL APPARATUS Filed Feb.

FIG].

I if; 2%} T 23 viq.

' Daniel .Noble B @2271? l 70 we): WHIP/4TH? INVENIOR.

ATTORNEYS Patented Aug..17, 1937 UNITED STATES PATENT OFFICE CONTROLAPPARATUS Daniel Earl Noble, st'or acorm. Application February 20, 1936,Serial No. 64,990

I 4 Claims.

My invention relates to control apparatus and has for its principalobject the provision of an improved limited impulse electronic relaywherein' an adjustable part controls the action of an electric valve toenergize for a predetermined time interval ,the coil of a relay or othercontrol device.

It is frequently desirable to have available an apparatus which willperform a control action either mechanical or electrical for apredetermined period, which period is adjustable in advance. Suchapparatus is especially useful in making photographic exposures where awide range of predetermined time intervals is needed and wherean-operator should be able to select such intervals with great accuracy.X I

The apparatus of my invention is intended to work directly from analternating current source of supply, without the interposition of anyspecial rectifying means, and its time interval is determined bythecharge of a condenser connected in the grid circuit of an electricvalve Fig. 1 shows one suitable circuit arrangement ior the apparatus ofmy invention and Fig. 2

shows a'modifled circuit arrangement of a similar apparatus.

In Fig. 1 is shown a circuit in for transmitting current from a suitablesource through a transformer II and an electric valve l2 to an 'electroresponsive device l3 which is shown as a relay coil adapted to controlthe connections of a circuit H which it is desired to control and whichmay comprise any desired apparatus such as a photographic printing lampor shutter arrangement. The valve I 2 comprises a grid ii forcontrolling the flow of current between its cathode i5 and its anode Hto the operating coil of the relay L1. The valve l2 may be of anysuitable construction and is here shown as a heated cathode type inwhich a filament I8 is the heater element. The transformer ii isprovided with a secondary winding IQ for supplying the current to theanode circuit of the valve l2 and another secondary'wlnding 20 forsupplying heating currentto the filament l8. It will be noted that thecoil of the relay i3 and the secondary winding is are connected inseries in the anode circuit of the valve l2 and that the grid i5 isconnected through a resistance 2| to the junction between the serialcombination of the relay coil I3 and the secondary winding i9 whereby anegative potential determined by the resistance of the coil I3 isimpressed on the grid I5. The 5 resistance 2| indicates any meanssuitable for regulating the impedance to the passage of a currenttherethrough such as a light sensitive cell or an ordinary adjustableresistance as shown.

In the arrangement shown the potential im- 10 pressed on the grid is, ofcourse, the drop across the relay coil l3 and a suitable seriesresistance 22, the value of which is so selected that the potentialapplied to the grid I5 prevents the anode current from reaching a valuesufliciently 15 large to actuate the relay l3. It will be understoodthat the additional resistance 22 is only necessary when the resistanceof the relay coil l3 does not supply the desired potential.

' A condenser 23 is adapted to be connected directly across the cathodel6 and the grid l5 by means of a switch 24 when it is in the positionshown in Fig.' 1. This switch 24 is normally to the left so as toconnect a lead 25 in shunt relation with the'condenser 23 so that thiscon- 25 denser is drained of any charge.

The operation of the apparatus will be readily understood if it beassumed that the switch 24 has just been moved to the position shown.Under this condition, the condenser 23 immediately 30 starts receiving acharge through the resistance M which decreases the potential on thegrid I5 by an amount equal to the drop across the resistance 2| and acurrent flows in the anode circuit of the valve H which energizes therelay 35 ii to close the circuit l4. As the charge on the condenser 23increases, the current through the resistance 2| decreases until theanode current of the valve l2 drops below the value at which the relayII will remain closed and, accord- 40 ingly, the relay opens the circuitII. The time intervalduringwhich the relay I3 is held closed dependsupon the magnitude of the capacity of the condenser 23 and the value ofthe resistance 2| and very accurate regulation of this time in- 45terval is possible by varying the capacity of the condenser 23 oradjusting thevalue of the resistance it included in the chargingcircuit. In the present instance I have shown the resistance 2| as beingvariable by means of an adjustable contact 26.

In the arrangement just described, it will be noted that the anodecurrent flows through the relay coil l3 only during one half of eachcycle oithe alternating current, and, in order-to e1im 55 2 I aoeasssinate any chattering of the relay i8. 1 connect a condenser 21 acrossthe relay coil 58, as is wellknown.

The embodiment of the invention illustrated in Fig. 2 is quite similarto the apparatus described 'in connection with Fig. 1 in that anelectric valve 30 controls the current flow in a relay 3| connected inits anode circuit and which con- I trols a separate circuit 32 by meansor a contact to 33 carrying an armature 34 adapted to he attracted uponenergization of the relay 3!. In the present instance, the valve 38 isof twin triode type which has its cathodes connected through the relay3! to the center point of the secondary winding 35 of a transformer 38,the primary winding 31 of'which is connected through'leads 38 to anysuitable source of alternating current. As is well known, the terminalsof the secondary winding 35 are connected to the anodes 39 and 40 of thevalve 30. The potential on the grids M and 42 of the valve 30 isdetermined by the potential drop across a resistance 43 due to thepassage therethrough of a charging current for a condenser 56. A switch,45, when in the poSi-' tion shown in Fig. 2, connects the condenser 54to be charged through the resistance 43 and. as was the case in thearrangement shown in Fig. 1, the potential on the grids of the valve isreduced and the anode current increases to 30 energize the relay 3i andthereby close the circuit 82 for a time interval depending upon thecapacity of the condenser 44 and the value of the resistance 43.Although the valve 38 is of the self rectifier type, I prefer to shuntthe relay Si with a condenser 52 toinsure quiet operation.

When the switch 45 is moved to its middle position, that is, engagingcontact 4 5, the condenser 64 is short circuited and the relay 3iremains open. If the switch 55 is moved to the extreme right so as toengage both the contact 46 and a contact 61 the cathode voltage isdirectly impressed on the grids of the valve 30 and the relay 3! holdsthe circuit 32 closed as long as the switch t5 remains in'this position.It is thus evident that this arrangement makes it possible for theoperator to obtain manually controlled time intervals. For adjusting thetime interval of the apparatus shown in Fig. 2, I have provided asliding contact 48 which acts to include a greater or less amount of theresistance 3 in the charging circuit in accordance with the position ofa dial knob 49 to which the contact 48 is secured. The knob 49 maybesecured to a disk 58 provided with a time scale which cooperates with anindex 5| to show the time interval for which the apparatus is adjusted.'Iin-each arrangement described the adjustable resistance for regulatingthe rate at which the so condenser is charged may take any desired formand may be adjusted either manually or auto-' matically in accordancewith any desired factor, such as the intensity of a light source, thetransmission of a, photographic record, or the like. as The embodimentsof my invention which have been illustrated and described have beenselected for the purpose of setting forth the principles involved. 'Itwill be obvious, however, that the invention-may be modified to meetvarious conditions which may be met with in difierent specific uses andI, therefore, intend to cover by the appended claims all suchmodifications which fall within the spirit and scope of my invention.

What I claim and desire to secure by- Letters Patent oi the UnitedStates is:

1. Means for controlling the current in the output circuit of anelectron discharge device having a cathode, anode, and controlelectrode, comprising an input circuit for said device, a source ofpotential in the output circuit, a resistance between the cathode andsaid source, a condenser one side of which is connected to the cathode,a resistance the value of which may be varied connected between thesource of potential and' the condenser so that the condenser is chargedthrough said variable resistance, and means for impressing the potentialdrop across said variable resistance, due to the charging current, uponsaid control electrode.

2. In an electric timing device including a relay coil connected in theoutput circuit of an electron discharge device having an anode, acathode,

and a grid, the serial combination of a resistance and a source ofpotential between the cathode and the anode, the resistance beingbetween said source and the cathode, a resistance the value of which maybe varied connected to the junction between said source and saidfirst-mentioned resistance and to the grid, a condenser, and means forconnecting the condenser across the grid and the cathode whereby thecondenser will be charged through the variable resistance at adiminishing rate until fully charged.

3.In a timing device including a relay coil, means for energizing therelay coil for a selected time interval comprising -a three electrodethermionic valve, a source of potential and said coil connected inseries across the cathode and anode of the valve so that said coil isbetween said source and the cathode, an adjustable resistance connectedacross the junction between said coil and said source and the controlelectrode of said valve, a. condenser, a switch for connecting thecondenser to be charged through said resistance,

and means for impressing the potentialdropacross said resistancedirectly upon said control electrode, whereby when the switch is closedan increased current will flow between said anode and said cathode toran interval of time depending upon the capacity of the condenser and themagnitude of saidresistance.

4. In a device of the character described including an electrondischarge device having a. cathode, an anode, and a grid, means forcontrolling. the potential of the grid. comprising a source of potentialconnected in series with a resistance across the cathode and the anode,the resistance being between the source oi potentialandthecathode,avariableresistanceconnectedbetween the grid and thejunction of the source or potential and the first-mentioned resistance,'a condenser, and means for connecting said condenser across the gridand the cathode wh r by the absolute value of the potential on said gridwill be reduced temporarily and will increase until said condenserbecomes chargedthrough said variable resistance.

DANIEL EARL NOBLE.

